Hole saw and reversible quick disconnect drive therefor

ABSTRACT

A hole saw equipped with a quick disconnect drive arbor having a pair of axially spaced threaded sections of opposite threaded direction with a non-locking included angle between the helices thereof of about 15*. A drive ring is mounted on the threads with the higher helix angle and a hole saw on the other threaded section. Rotation of the drive ring and hole saw in unison relative to the drive shaft in one direction causes the bottoming of the drive ring and the hole saw for transmitting torque. Reverse rotation quickly disconnects the hole saw from the arbor. To accommodate the use of the drive arbor with a reversible power unit, a locking ring having a non-circular aperture is slidably mounted around a mating portion of the arbor and is rotatable around a reduced cross section neck of the arbor to a locking position to prevent axial movement of the drive ring upon reverse rotation of the shaft. The neck of the arbor is provided with lobes forming stops to establish the locking and non-locking position of the lock ring. A compression spring frictionally engages the drive ring and the locking ring to resist relative rotation and to urge the locking ring away from the drive ring in the non-locking position thereof.

United States Patent [191 Bittern HOLE SAW AND REVERSIBLE QUICKDISCONNECT DRIVE THEREFOR [75] Inventor: Joseph E. Bittern, Weatogue,Conn.

[73] Assignee: Capewell Manufacturing Company,

Hartford, Conn.

[22] Filed: July 12, 1972 [21] Appl. No.: 271,039

[52] US. Cl 408/204, 144/20, 144/23,

287/53 R, 151/16, 279/1 B, 408/703 [51] Int. Cl B23b 51/04 [58] Field ofSearch 408/191, 196, 204,

[56] References Cited UNITED STATES PATENTS 972,669 10/1910 Wilt l5l/172,482,439 9/1949 Smith 144/23 X 2,562,327 7/1951 Moore 287/53 R X3,697,310 3/1972 Morse 408/209 Primary Examiner-Andrew R. JuhaszAssistant Examiner-Z. R. Bilinsky Attorney-John M. Prutzman et a1.

[ Jan. 8, 1974 [57] ABSTRACT A hole saw equipped with a quick disconnectdrive arbor having a pair of axially spaced threaded sections ofopposite threaded direction with a non-locking ineluded angle betweenthe helices thereof of about 15.

A drive ring is mounted on the threads with the higher helix angle and ahole saw on the other threaded section. Rotation of the drive ring andhole saw in unison relative to the drive shaft in one direction causesthe bottoming of the drive ring and the hole saw for trans mittingtorque. Reverse rotation. quickly disconnects the hole saw from thearbor. To accommodate the use of the'drive arbor with a reversible powerunit, a locking ring having a non-circular aperture is slidably mountedaround a mating portion of the arbor and is rotatable around a reducedcross section neck of the arbor to a locking position to prevent axialmovement of the drive ring upon reverse rotation of the shaft, The neckof the arbor is provided with lobes forming stops to establish thelocking and non-locking position of the lock ring. A compression springfrictionally engages the drive ring and the locking ring to resistrelative rotation and tourge the locking ring away from the drive ringin the non-locking position thereof.

9 Claims, 3 Drawing; Figures 1 HOLE SAW AND REVERSIBLE QUICK DISCONNECTDRIVE THEREFOR BACKGROUND AND SUMMARY OF THE INVENTION The presentinvention relates generally to a hole saw and is an improvement upon theinvention described and claimed in my copending patent application Ser.No. 271,040 entitled Hole Saw and Quick Disconnect Drive Therefor filed(Our Ref: Capewell Case 33 executed July 7, 1972) Hole saws of the typeinvolved in this invention are generally driven by a portable powerunit, e.g., an electric drill. Many such power units are equipped withreversing switches to provide reverse rotation for the output spindleand are reversed to assist in the extraction of the drill or otherdriven tool from the work piece. With users being accustomed to thisoperating procedure, it is important for a rotary drive coupling for ahole saw to accommodate this customary procedure in the removal of thehole saw for the work piece and it is the principal object of thisinvention to provide a foolproof, simple and inexpensive solution forthis problem.

Another object of this invention is to provide a new and improved quickrelease drive arbor assembly for hole saws and the like whichaccommodate the reverse rotation retraction of the tool from theworkpiece. Included in this object is the provision of an axiallymovable and rotatable lock in which positive stops are provided to fixthe rotational positions for locking and unlocking.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

A better understanding of the invention will be obtained from thefollowing detailed description and the accompanying drawing of anillustrative application of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is an elevational view, partially in section, of a hole saw andarbor assembly embodying the features of the present invention;-

FIG. 2 is a cross-sectional view taken along the lines 2-2 of FIG. 1;and

FIG. 3 is a cross-sectional view taken along the lines 3-3 of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing ingreater detail, the present invention, for clarity of illustration andease of understanding, is shown and described as embodied in a hole saw.

As morefully described in my copending application Ser. No. 27l,040, thehole saw and arbor assembly of the present invention is shown in thedrawing as consisting of a drive shaft 10, a drive ring 12, a hole saw14, the drive ring 12 and the hole saw 14 being adapted for threadedmounting on the drive shaft.

The shaft is shown as being provided with a central bore 16 extendingaxially along its length for receiving a suitable pilot drill (notshown) which can be conveniently secured within thebore 16 by a setscrew 18 As shown, a pair of adjacent threaded screw sections 22, 24spaced by an unthreaded groove 23 are provided on the drive shaft 10adjacent its lower end.

The threaded section 22 positioned remote from the lower end of thedrive shaft 10 has a left hand thread while the threaded section 24 hasa right hand thread.

Threaded section 24 is shown as being a single thread configurationwhile the threaded section 22 is shown as being of a multiple threadconfiguration with the included angle between the helices of the threadsof sections 22, 24 being a non-locking, or self-releasing, anglesufficient, say 15 or more, to permit the easy manual removal of thehole saw 114 without the necessity of an auxilliary assembly tool suchas a key.

The drive shaft 10 is provided with an annular flange 20 shown as beingformed integrally with the shaft.

In the preferred embodiment, the threaded section 22 is provided withthe higher helix angle and the threaded section 24 is provided with aconventional screw thread to accommodate cup shaped hole saws 14 of thetype currently available in the market.

The quick disconnect drive ring 12 has a central threaded aperture forthreadably engaging the left hand threaded section 22 of the drive shaft10, the threaded section 24 being of reduced diameter to allow the drivering 12 to pass thereacross. The drive ring 12 is provided with adepending pair of diametrically opposed aligning and drive pins 26affixed thereto as by being pressed in axial holes therein with a pressfit.

As will be appreciated from the foregoing description, the hole saw iseasily assembled on the quick dis connect drive arbor by initiallyrotating the drive ring 12 of the threaded section 22 to its upperposition where the ends of pins 26 lie in a plane perpendicular to theaxis of the drive shaft 10 and passing through the groove 23. The holesaw 14 is then rotated onto the threaded section 24 until bottoming onthe ends of the aligning and drive pins 26. Thereafter the hole saw isbacked off, less than until the pins register with the apertures 36 ofthe tool. Thereafter a slight further forward rotation of the hole saw14 in unison with the drive ring 12 will rapidly draw the drive ringinto hottoming contact with the saw.

When so assembled, the drive ring provides a solid stabilized support toreinforce the end wall 14a of the hole .saw 14 and the use of theopposite threaded sections 22, 24 automatically produces an axialbiasing force on the hole saw 14 maintaining it against in solid contactwith drive ring 12 as a result of the torque required to rotate the holesaw during use. This prevents any vibration due to relative movement orplay between the threads of the hole saw and the threaded section 24resulting from the normal thread clearances and also produces a biasingforce which increases in proportion to the torque loading imposed on thehole saw 14 as more fully described in my copending patent application.

To remove the hole saw 14 from the drive shaft 10, it is merelynecessary to rotate the hole saw in the same clockwise direction ittravels during use while holding the shaft 10 stationary. This causesthe drive ring 12 to move axially away from the hole saw 14 along themultiple threaded section 22 to effect the rapid separation of the holesaw and the drive ring. As soon as the aligning and drive pins 26 clearthe apertures of the hole saw, continued rotation of the hole saw 14alone removes the hole saw from the threaded section 24 of th driveshaft.

As heretofore stated, hole saws of the type involved in this inventionare often driven by a portable electric power unit, such as an electricdrill, many of which are provided with reversing switches to facilitatethe removal of the tool from the work piece.

In accordance with this invention, means are provided for preventing thedisconnecting of the hole saw 14 from the drive shaft during suchreverse rotation and to allow the hole saw to be removed from theworkpiece in the customary manner ofa tool provided by an operatorhaving a reversing switch.

As shown in FIG. 2, the flange is generally cylindrical in cross sectionwith a pair of parallel flats 38 on opposed sides thereof. The axiallyslidable and rotatable locking ring 40 has, as shown in FIG. 2, an innerperiphery 42 having a similar cross sectional configuration so that itis axially slidable on flange 20. A conical spring 44 is provided tobias the locking ring upwardly with respect to the drive ring 12. Thelock ring 40 is provided with an annular recess 46 of sufficient depthto receive the conical spring therein. The flange 20 has a neck 48having the cross section shown in FIG. 3 for purposes hereinafter morefully described. A groove is provided in the flange 20 for receiving aresilient wire ring 50 which serves as a stop to limit the uppermovement of the lock ring 40.

With the drive ring 12 and the hole saw 14 bottomed against each otheras shown in FIG. 1, the lock ring 40 is pushed axially downwardly alongthe flange 20 guided by the flats 38, and flats 48a of neck 48 which liein the plane of flats 38, against the bias of the spring 44 until itengages the drive ring 12 as shown in phantom in FIG. 1.

As best shown in FIG. 3, the neck 48 of the flange 20 has a second pairof opposed parallel flats 48b which cooperate respectively with theflats 48a to form a pair of lobes 48c. Pairs of flats 48a and 48b areformed on a tangent to circular portions 48d with the circular portionshaving a diameter substantially equal to the distance between the flats42a of the locking ring 40.

With this construction, it can be seen that when the locking ring 40 isengaged with the drive ring 12 it lies in the plane of the neck 48 andmay be rotated to the right as viewed in FIG. 2 until the flats 42aengage the flats 48b of the neck 48 which serve as stops to prevent thefurther rotation of the lock ring 40 and positively locate the lock ringin locking position with its flats 42a in a position beneath theshoulders 20a (FIG. 1).

The ring 40 is provided with an annular recess 52 which cooperates withthe circular portion of the flange 20 to maintain the lock ring 40concentric with the drive shaft at all points of rotation. Theengagement between the ends of conical spring 44 and drive ring 12 andlock ring 40, respectively, serve to maintain the lock ring againstrotation during the use of the hole saw.

When it is desired to remove the saw 14, all that is necessary is torotate the lock ring counterclockwise, as viewed in FIGS. 2 and 3, untilthe flats 42a of the lock ring engage the flats 48a of the neck 48 toprovide positive and accurate alignment and easy axial movement of thelock ring under the bias of the spring to a position against wire ring50. a

The hole saw 14 may then be removed from the drive shaft 10 by rotationof the hole saw 14, and drive ring 12 clockwise relative to drive shaft10.

As will be apparent to persons skilled in the art, variousmodifications, adaptations and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

I claim:

I. In a hole saw assembly equipped with a quick disconnect rotatabledrive arbor including a drive shaft having first and second threadedsections of opposite thread direction, the included angle between thehelices of the threaded sections being a non-locking angle, a drive ringthreadably mounted on one of said threaded sections, and a hole sawthreadably mounted on the other of said threaded sections for rapidassembly and disassembly of the hole saw and the drive shaft; theimprovement comprising a locking ring mounted on said shaft, saidlocking ring being rotatable to locking position where it prevents theaxial movement of said drive ring upon reverse rotation of said arborand to a non-locking position where it accommodates axial movement ofsaid drive ring upon reverse rotation of said arbor.

2. The device of claim 1 wherein said drive arbor is provided withradial shoulder means and said locking ring is provided with shouldermeans which engages said radial shoulder means in locking position.

3. The device of claim 2 wherein a biasing spring is positioned betweensaid locking ring and said drive ring.

4. The device of claim 3'wherein said spring frictionally engages saidlocking ring and said drive ring to resist relative rotation.

5. The device of claim 2 wherein said drive arbor has a neck of reducedcross section to provide said radial shoulder means.

6. The device of claim 5 wherein said neck has a noncircular peripheryhaving walls providing lobes and the locking ring has a non-circularaperture having walls engageable therewith to limit relative rotationtherebetween and establish the locking and non-locking positions of saidlocking ring.

7. The device of claim 6 wherein said arbor adjacent said neck has anon-circular periphery which mates with said non-circular periphery ofsaid locking ring to accommodate relative axial sliding movementtherebetween.

8. The device of claim 7 wherein the walls of said neck establishing thenon-locking position of said locking ring are axial extensions of wallsof the adjacent non-circular periphery of the arbor to guide the lockingring in its axial sliding movement in its non-locking position.

9. The device of claim 6 wherein the non-circular aperture of saidlocking ring is formed in a recess defined by a circular walldimensioned to engage the periphery of said arbor adjacent said neck tomaintain the locking ring concentric with said arbor during the rotationthereof between its locking and non-locking positions.

1. In a hole saw assembly equipped with a quick disconnect rotatabledrive arbor including a drive shaft having first and second threadedsections of opposite thread direction, the included angle between thehelices of the threaded sections being a non-locking angle, a drive ringthreadably mounted on one of said threaded sections, and a hole sawthreadably mounted on the other of said threaded sections for rapidassembly and disassembly of the hole saw and the drive shaft; theimprovement comprising a locking ring mounted on said shaft, saidlocking ring being rotatable to locking position where it prevents theaxial movement of said drive ring upon reverse rotation of said arborand to a non-locking position where it accommodates axial movement ofsaid drive ring upon reverse rotation of said arbor.
 2. The device ofclaim 1 wherein said drive arbor is provided with radial shoulder meansand said locking ring is provided with shoulder means which engages saidradial shoulder means in locking position.
 3. The device of claim 2wherein a biasing spring is positioned between said locking ring andsaid drive ring.
 4. The device of claim 3 wherein said springfrictionally engages said locking ring and said drive ring to resistrelative rotation.
 5. The device of claim 2 wherein said drive arbor hasa neck of reduced cross section to provide said radial shoulder means.6. The device of claim 5 wherein said neck has a non-circular peripheryhaving walls providing lobes and the locking ring has a non-circularaperture having walls engageable therewith to limit relative rotationtherebetween and establish the locking and non-locking positions of saidlocking ring.
 7. The device of claim 6 wherein said arbor adjacent saidneck has a non-circular periphery which mates with said non-circularperiphery of said locking ring to accommodate relative axial slidingmovement therebetween.
 8. The device of claim 7 wherein the walls ofsaid neck establishing the non-locking position of said locking ring areaxial extensions of walls of the adjacent non-circular periphery of thearbor to guide the locking ring in its axial sliding movement in itsnon-locking position.
 9. The device of claim 6 wherein the non-circularaperture of said locking ring is formed in a recess defined by acircular wall dimensioned to engage the periphery of said arbor adjacentsaid neck to maintain the locking ring concentric with said arbor duringthe rotation thereof between its locking and non-locking positions.